Microbiological Profile of ‘Ogiri’ Condiment Made from Seeds of Watermelon (Citrullus lanatus)

Introduction: Condiments are essential part of the diet of various cultures in different parts of the
world. Its consumption continues to increase due to some factors that include population growth and
increased consumer preferences. A condiment refers to a substance that is added to food to impact a
particular desired flavour or texture to the dish. ‘Ogiri’ refers to a fermented oily paste that is used as
soup condiments for its strong smell. It is a product prepared by traditional method of uncontrolled
solid state fermentation of castor bean (Ricinus communis) and/or melon seeds (Citrullus vulgaris),
involving the use of natural inoculation or chance fermentation.
Aim: This research work was conducted to evaluate the microbiological profile of ‘ogiri’ condiment
made from the seeds of watermelon (Citrullus lanatus).
Study Design: This work was a laboratory experimental design study.
Place and Duration of Study: Dept. of Microbiology (Food and Industrial unit), Nasarawa State
University, Keffi, between March and April, 2017.
Methodology: Traditional method of ‘ogiri’ production was adopted to prepare the sample in
replicates to facilitate the 24-hourly microbiological evaluations. Microbial isolation and identification
were done using standard microbiological techniques. Also, laboratory-controlled fermentation was
carried out using the isolates obtained from traditional fermentation as starter- cultures.
Results: The result of the traditional fermentation of the watermelon seeds yielded an oily brownish
paste that has a strong characteristic pungent aroma. The result of the microbial enumeration showed
that bacteria were present throughout the period of fermentation in an increasing population that
ranged from 32x101 cfu/g at the starting time (Day 0) to 288 x106 cfu/g at the end of the fermentation
period (Day 5). There was no fungal growth at the beginning of the fermentation, till on Day1 (8x103
cfu/g) to the Day 5 (6x106 cfu/g). The isolation of the coliform group of bacteria showed an unusual
growth pattern: no coliform isolated from the freshly boiled seeds, coliform was present at Day 1 and
2, and no isolation of coliform bacteria from Day 3 to the end of the fermentation period (Day 5). Over
the 5-day period of fermentation, the organisms isolated and identified are Bacillus subtilis,
Corynebacterium xerosis, Lactobacillus fermenti, Staphylococcus saprophyticus, Staphylococcus
aureus, Citrobacter freundii, coliform bacteria, yeast and mould.
Conclusion: Hence, it was concluded that ‘ogiri’ condiment can be made from watermelon seeds,
using Lactobacillus fermenti, Corynebacterium xerosis and/or Bacillus subtilis as starter cultures. The
results obtained from the study have shown the prevalence of bacteria throughout the period of
fermentation in an increasing population. Fungi and coliform group of bacteria were not isolated at the
beginning of the experiment till after 24 hour of commencing the fermentation process. Filamentous
fungi (mould) growth was obtained only after the fifth day of fermentation, thereby suggesting it to be
spoilage growth. Bacillus spp. was isolated throughout the fermentation period, thereby proving to be
major fermentative organisms. The result of the laboratory-controlled fermentation confirmed that
‘ogiri’ condiment could be obtained with Lactobacillus fermenti, Corynebacterium xerosis and/or
Bacillus subtilis starter cultures. However, it is recommended that the products of this study should be
further assessed for any possible toxicology study before it can be wholly acceptable for human
consumption.